The processing resolution in photolithography technology, which forms the basis of semiconductor processing technology, has generally been improved by shortening the wavelength of the exposure light. For example, the resolution in EUV lithography technology that uses extreme ultraviolet light (EUV, wavelength 13.4 nm) is, currently, in the region of 20 nm to 30 nm. Nevertheless, because EUV exposure process is impossible in environmental atmosphere (i.e., under non-reduced pressure) as well as the equipment itself is very expensive, EUV lithography is not expected to be used widely.
Further, it has been learned that an exposure apparatus that uses an excimer laser (ArF, wavelength 193 nm) as a light source and an immersion lens for an optical system has a processing resolution of 30 nm, and thus extensive research into mass production of such an apparatus is being carried out. However, the limits of processing resolution based on wavelength have already been reached, so that a dramatic improvement in resolution is not anticipated. Therefore, it is expected that improvements in integration density and performance in semiconductor processing will reach their limit in the near future.
On the other hand, lithography technology that utilizes near-field light is known. This technology patterns a photoresist by utilizing the near-field light generated at the ends of a nanostructure.
An example of a competing nanopatterning technology is nanoimprinting. However, nanoimprinting suffers from the drawback that separation between the mold and the resist substrate is difficult.